@ Tarek -This is false. These types of links are best for helping to give newer sites a boost in backlinks and helping to get your site indexed quickly. You can point them at older sites, but they won't do to much for as far as rankings.
If Google did not notice them, they would not help with getting newer sites ranked.
Just because the links themselves aren't showing up in a backlink checker tool immediately or ever, that does not mean the link does not exist.
Google is the worst place for checking backlinks because they filter their results very heavily and only show what they want. If you check Google to see how many backlinks they saythey have to themselves, it is only 18,500.
Yahoo site explorer is probably one of the most accurate, but not 100%.
The bottom line is that, although not the best types of links, these links do have a small purpose and should not be discounted.